How do mineral sunscreens work differently from chemical sunscreens?

Mineral sunscreen sits on your skin and reflects/scatters UV like tiny mirrors, while chemical filters absorb UV and convert it into heat. Mineral sunscreens start working immediately and are less likely to irritate sensitive skin, but they can leave a white cast and feel thicker. Chemical sunscreens feel lighter and rub in clear, but need 20 minutes to become effective and may cause reactions in some people.